OK, but here are your outcomes if you are good at X and need X and Y:
You do X, hire Y - You have one skilled person, one question mark.
You do Y, hire X - You have one unskilled person, one question mark.
Seems pretty simple to me that the first is better. I suppose that you could make the argument that Y may be easy to pick up, but if that's the case it should be all the easier to just hire someone else with a proven track record.
My thought exactly, those two question marks aren't equal. One I am capable of evaluating, both before and after I hire for the position. The other I am incapable of evaluating both before and after I hire for the position.